Embodiments herein generally relate to electrostatographic printers and copiers or reproduction machines, and more particularly, concern a pressure role used in conjunction with a vacuum belt.
One exemplary embodiment herein comprises a printing apparatus that can include a printing engine that prints markings on sheets of media. The sheets of media that are printed upon (and/or sheets that are scanned) can be transported using belts, such as vacuum belts that generally include a plurality of vacuum openings which hold the media sheets using vacuum force (suction). Thus, the vacuum belts transport the media sheets relative to the printing engine. Often, it is advantageous to use one or more pressure rolls that contact the vacuum belt. The sheets of media pass between the pressure roll and the vacuum belt. Thus, the pressure roll presses the media against the vacuum belt and flattens out the media sheets on the vacuum belt. Embodiments here use a pressure roll that comprises at least two offset roll segments.
The pressure roll segments are connected to a common axle and each pressure roll segment contacts the vacuum belt. With embodiments herein, the roll segments are offset from one another along the vacuum belt. The vacuum belt moves in a first direction (a sheet path direction) that is parallel to the edge of the vacuum belt. The roll segments contact the vacuum belt at different locations along the first direction.
The roll segments are substantially identical to one another in size and shape. Each of the roll segments comprises a substantially identical center through which the common axle passes. All the centers of the roll segments are positioned the same distance from the vacuum belt; however, the centers of the roll segments are offset from one another along the first direction of the vacuum belt. The common axle passes through the centers of the roll segments. Because the roll segments (and the centers) are offset along the first direction, the axle is non-perpendicular to the first direction. In other words, the axle is positioned angled (at an angle other that 90°) with respect to the linear edge of the vacuum belt.
Each of the roll segments comprises a curved, flattened outer surface contacting the vacuum belt. The curved, flattened outer surfaces of the roll segments intersect the curved, flattened outer surfaces of adjacent roll segments at only two points because the roll segments are offset from one another.
These and other features are described in, or are apparent from, the following detailed description.